When I bought my 68 Bird, it had incorrect "Bullet" style mirrors on it. While it looked nice, the 68 never had the bullet style available and the mirror appeared to be not working. The (LH Driver) bullet mirror was held on by two Phillips head screws. When I took the mirror off, I was surprised to find a mechanical remote which had been laying in the door panel. The remote cable came out through a 7/8 hole.
I drove 3 hours round trip to the NPD in Ocala and spent $130.00 on two Scott Drake rectangular style mirrors which the salesman guaranteed me were the best and would fit as there was only one door style for 68 Camaro and Firebirds. I took them home and was shocked to find the mounting was different. What NPD sold me had a small bracket which appears to somehow screw onto the door and then the mirror is held on by a set screw. Also, the base of the NPD mirror would be too skinny to cover the 7/8 hole in the door.
After looking around on the site, I read one post stating some of the first 68s had round mirrors. Please help me find chrome mirrors which will fit.